Rotary take-up sewing machine



Feb. 24, 1959 DENZABURO TERAYAMA Y EIAL 2, 74,

' ROTARY TAKE-UP sswmc MACHINE J Filed Aug. 30, 1955 v 6 Sheets-She'et l Feb. 24, 1959 DENZABURO TERAYAMA ETAL 2,874,665

ROTARY TAKE-UP SEWING MACHINE Filed Aug. 30, 1955 6 Sheets-Sheet 2 Feb, 24, 1959 DENZABURO TEIRAYAIYMA ETA].

. ROTARY TAKE-7UP SEWlNG MACHINE a Sheets-Sheet 3 Fil ed Aug; 50. 1955 DENZABURO TERAYAMA ET AL 2,874,665

Feb. 24, 1959 ROTARY TAKE-UP SEWING MACHINE 6 Sheets-Sheet 4 Filed Aug. 30, 13 55 v flax x & Feb. 24, 1959 w 'DENZABURQ TERAYAMA ETAL 2,874,665

ROTARY TAKE-UP SEWING MACHINE Filed Aug. 50, 1955 s Sheets-Sheet 5 Feb. 24, 1959 DENZABURO TERAYAMA ETVAL 2,874,665

ROTARY TAKE-UP SEWING MAcHINE Filed Aug. 50, 1955 e Sheets-Sheet e United States Patent ROTARY TAKE-UP SEWING MACHINE Denzaburo Terayama and Tom Matsubara, Chofu-shi, Tokyo, Shigeki Hayashi, Tokyo, and Yotaro Hirakawa, Nakano-ku, Tokyo, Japan, assignors to Tokyo Juki Kogyo Kabnshiki Kaisha, Tokyo, Japan, a corporation of Japan Application August 30, 1955, Serial No. 531,383 Claims priority, application Japan September 18, 1954 Claims. (Cl. 112-248) This invention concerns a single shaft thread take-up device type household sewing machine comprising a halfoscillating type shuttle. It has for its object the provision of a household sewing machine having various merits peculiar to the single-shaft-type thread take-up device and also several advantages claimed for the half-oscillating type shuttle, by making the characteristic curve of its single-shaft-type thread take-up device roughly the same as that of the usual cam-type thread take-up device, and also having the device by which a fine result can be achieved in sewing by the speedy completion of rational supply, the pulling-up of the thread and the tightening of the cloth by the thread.

The existing camtype thread take-up device has not been free from such disadvantages as difficulty of highspeed operation, annoying noises, serious abrasion, and lack of durability. As the basic solution of these defects, it may be considered that the single-shaft-type thread take-up device will be adopted instead of the above device, thereby to secure a household sewing machine of outstanding merits in respect of ability to make highspeed operation, freedom from noises and abrasion, and with. high durability. However, implementation of this conception has been in practice difiicult for the following reasons:

More particularly, a sewing machine equipped with the single-shaft-type thread take-up device has been necessarily regarded as unsuitable for use as a household sewing machine, since it employs a twice-rotation-type shuttle, has a somewhat small stroke, and therefore is very fitting for use as an industrial sewing machine with a large angle of taking up sewing thread. Whereas it is required in the case of a household one that a half-oscillating-type shuttle is used; that the stroke is rather larger; and that the angle of rotation of main shaft necessary for pulling up thread to the uppermost is small. Further, it is required, employing the sewing machine equipped with thread take-up device as industrial sewing machine, that the angle 1,!1 of rotation of the main shaft for pulling the sewing thread to the uppermost should be approximately 120 degrees and the stroke S about 115 mm., while in employing the same machine as household onethe angle 0 required should approximately be 90 degrees and the stroke 8 about 125 mm. The sewing machine equipped with the thread take-up device is subject to such restrictions in point of capacity. At the same time it was difiicult in the case of the said sewing machine to make its curve of variation of the amount of take-up of the sewing thread correspond to the curve of variation of the amount of the sewing thread drawn in under the needle-plate of the half-oscillating type shuttle of a household sewing machine, with the result that the former has come to be considered unfitting for household use. The inventors have succeeded in completing the present invention only after assiduous efforts devoted to construct a sewing "ice machine with single-shaft-type thread take-up device which may also perform the functions of a household sewing machine.

According to one aspect of this invention, there is provided, in a sewing machine, a device for taking up the sewing thread including a plurality of disks concentrically attachedto a main shaft one above another with a plurality of sewing thread take-up members such as inserted between the adjacent disks, thus forming dou-ble passages for taking up the thread by means of a threadguide for turning the thread; and the above-mentioned device for taking up the sewing thread comprises a means for causing asid disks to rotate at a nonuniform velocity in relation to said main shaft, said means comprising a double crank mechanism conditional on where E is the eccentricity between said two axes, that is,v

where r is the distance between the axis of one of. said take-up members and said common axis, r is, the-distance between the axis of another of said take-up members and said common axis; a(= PCQ) is the angle between. I

the last-named two distances, 0 ACB) is the angle between the distance between said feeding guide and said common axis and the distance between said turning guide and said common axis and larger than and smaller than and 0 DCB) is the angle between the distance between said delivery guide and said common axis and the distance between said turning guide and said common axis, and said arrangement further satisfying such a condition where 6(= PCB) is the angle between the distance between said turning guide and said common axis and the distance between the last-named take-up member and said common axis when said needle rod is in the highest position, therefore it is possible that the angle 11/ of rotation of the main shaft necessary for pulling up the sewing thread to the uppermost is narrowed approximately to 80 degrees.

Thus, by making the characteristic curve of the singleshaft-type thread take-up device roughly the same as that in the usual earn-type thread take-up device which employs a half-oscillating type shuttle, and also having the device by which a fine result can be achieved in,

v3 pulling-up of the thread and the tightening of the cloth by the thread, we have succeeded in constructing a household sewing machine provided also with the various advantages claimed for the single-shaft-type thread take:

up device.

This invention will be described further, by way of example, with reference to the accompanying drawings, in which:

Fig. 1 is a perspective view of the head as partly cutoif. Fig. 2 represents a cross-section of the front of the head which is shown as partly cut off. Fig. 3 is a side view of the head. Fig. 4 is an illustration of the close relation between the crank on the side of thread take-up device, the link rod and the crank on the side of main shaft. Figs. 5 to 8 are the side views of the sewing machine which show each the state of the crank on the side of the thread take-up device as it revolves at angles of zero, 90, 180, and 270 degrees respectively. Figs. 9-a and 9-b are the graphs showing the close relation between the curve of variation of the amount of take-up of the sewing thread and the curve of variation of the amount of the sewing thread drawn in under the needle-plate, and the resulting curve of variation of the amount of loosening of the sewing thread. Fig. 10 is a linear diagram showing the relation between the angle at which the crank on the side of main shaft revolves and the angle at which the crank on the side of thread take-up device revolves. Fig. 11 is a front view showing the location of pin on the thread take-up device. Fig. 12 is a linear diagram showing the curve of variation of the amount of take-up of the sewing thread marked by the thread take-up device in rotating at uniform velocity. Fig. 13 is a linear diagram showing the curve of variation of the amount of take-up of the sewing thread into which the curve drawn by Fig. 12 changes according as the thread take-up device revolves at nonuniform velocity. Fig. 14 is a front view of the close relation between the sewing thread take-up members on the thread take-up device and the thread-guide when the needle is in the highest position. Fig. 15 is a linear diagram showing the variation in the curve of variation of the amount of the take-up of the sewing thread as the position of the sewing thread take-up pin on the outer side in Fig. 14 is caused to change within the fixed range of tolerance. Fig. 16b is a side view of the thread take-up device of Fig. 11 modified to include a third auxiliary pin and Fig. 16a is a diagrammatic front view thereof showing the relative locations of the pins P, Q and R. Fig. 17 is a diagrammatic front view of the thread pick-up device showing the movement of the sewing thread and illustrating the relationship, during operation, between the thread, the take-up pins and the thread cutter. Fig. 18 is a diagrammatic front view of the modification of Figs. 16a and 1612 wherein two circular discs are provided and two pairs of pins are provided and are set on points slightly out of mutually corresponding positions.

Figure 19 shows a diagram comprising curves of variation in the amount of take-up of the sewing thread, a curve representing the case where the third, thread take-up pin R is shown so as to compare the former with the latter. Figure 20 shows a diagram comprising three curves, two curves representing the variation in the amount of takenup threads supported by the inside and outside pins, respectively, and the third curve representing the composite variations composed of the above two variations. Figure 21, corresponds to Figure 14 but shows the third, thread take-up pin R. r

In Figs. 1 to 5, 1 represents a single-shaft-type take-u device, in which two thread take-up pins 13, 14 are inserted between two disks, inner and outer, 11, 12. In this example of the invention shown in the accompanying drawings, if the centers of such pins are indicated by P and Q, if the center of rotation of disks 11, 12 is C, if the positions of the thread-guides are A, B and D, where the lengths CI and C Q are r and r respectively, and if Q=a, ACB=0 and DCB=0 then r =24.6 71:36.5 therefore a=111 0 137 02:]. 0 therefore In addition, when the needle is in the highest position as shown in Fig. 14, the position of the pin 13 is decided by the following condition where 6(= PCB) is the angle between the centre of pin P and the thread-guide for turning the thread. 2 is the crank by which the thread take-up device is made to work. This crank is devised particularly to be disk-shaped and set on the side-wall of machine-head 16 so as to operate freely. 3 is the crank connected with the main shaft 7 and the radius of the crank (HE=R is half the stroke S of the needle rod 15. 6 is the link rod connecting the above-mentioned two cranks 2, 3, and its length (F G =L),

the crank radius (fi=R of the crank on the above- :mentioned thread take-up device, the length of eccentricity E between the centers C, H of the above-mentioned two cranks 2, 3, and the radius of the crank on the aboveunentioned main shaft are as follows:

R =9.4 therefore And the angle of eccentricity 5 formed by the straight line linking the centers of both cranks C, H and the needle rod line 8 is as following, in this example of the invention shown in Fig. 3,

The close relationship between the becoming nonuniform of the velocity of the thread take-up device according to the aforesaid construction, changes in the relative positions of the pins P, Q, the thread-guides A, B, D within the fixed range and the curve of variation of the amount of take-up of the sewing thread by means of the thread take-up device are shown in Figs. 10 to 15.

Fig. 10 represents the relationship between the angle at which the crank on the side of the thread take-up device revolves and the angle to at which the crank on the side of the main shaft revolves when the disk 11 is caused to rotate at nonuniform velocity under the conditions as set out by the above-mentioned expressions S, T, U, and W, wherein the ordinate Y gives the angle of rotation of the crank on the side of the thread take-up device and the abscissa X the angle 0. of rotation of the crank on the side of the main shaft. Curve SS indicates the allowable margin. In the example of the execution above, the variable speed curve is represented by curve T, which lies between curve S and curve S.

In addition, curves of variation of the amount of takeup of the sewing thread in both cases, i. e., where the thread takeup device rotates at uniform velocity as indicate'dinFig. 14 and wher'e it rotates at nonuniform ve locity as inthis invention, are shown in Figs. '12 and 13,

respectively, wherein the ordinate Y gives the amount of: take-up of the sewing thread and the abscissa X the angle thread take-up pins P, Q and thread-guides A, B and D are caused to change within the range of expressions I, K,M and N referred toabove, and curves A and B in Fig. .13 each corresponds to curves A and B.

..In' Fig. 15 in which the ordinate Y shows the amount of take-up of the sewing thread and the abscissa X the angle of the main shaft, it is shown that, when the position of the sewing thread take-up pin P in the phase of the upper dead point of the needle rod is made to lie within the range given by expression N, the phase of the upper dead point of the take-up device lies within the range of 55 to 75 in relation to the phase of the upper dead point of the needle rod. And the phase of the upper dead point of the take-up device is required to lie within this specific range, if satisfactory performance of sewing as a household sewing machine is desired at all.

In Figs. 1 to 3, 4 is a thread-cutter which is devised to cut off andremove the sewing thread as it snaps. Further, for the convenience, of setting the thread-cutter 4, of the two disks 11, 12, the outer one 11 is made hollow. Details of the position of setting the thread-cutter are given in Fig. 17.

In Fig. 17, 20 is an imaginary circle touching an imaginary line PQ joining the center of outer pin P and that of inner pin Q with its center at the center of the disk C. To.this imaginary circle 20, two imaginary tangents 15 1 and T337, the former from D, the center of the lower thread-guide 19 and the other from B, the center of the thread-guide 18 for turning the sewing thread are drawn so as to meet somewhere within the area of the triangle ACBD and the blade 21 of the thread-cutter 4 is set in the region of the circular sector FGH defined by the two imaginary tangents, and RN, and the inner periphery 38 of the circular disk 11. When the thread accidentally snaps during the sewing operation, it is immediately touched and cut oif by the blade 21 of the threadcutter 4 and removed out of the rotary orbit of the disk 11 due to the centrifugal force, whereby the operation after the accident is safely continued. As the whole arrangement is a single shaft complex disk type thread take-up device, the disadvantage of the entangling of thread about one of the two disks which has not the blade owing to the incomplete operation of the threadcutter experienced often in some generally known devices in which the blade of the thread-cutter is attached to one of the two circular disks is entirely removed, and in addition, in the normal operation, the blade 4 will not touch the sewing thread 10 at all. This fact will be explained by referring to Fig. 17.

At first, the passage or course limit of the thread passing through the lower thread-guide D in the nearer side of the blade of the thread-cutter 4 in the disk 11 will be described. The thread passing through the lower threadguide D will not come to any part of the right side of the position where the points D, P and Q are on the same straight line. Let us call P and Q in this special position as P and Q In this special position, P is in contact with 56 and if it rotates still more, the thread passing through D will be forced to change its course by P. That is why the thread passing through the lower thread-guide D will not come to any part of the right side of this special position.

The position on which the points D, P and Q are on a same straight line is the position occupied by the tangent drawn from D to the circle 20 whose radius is the .length r6, 0? a perpendicular li f C to m The line DP Q is expressed in the rectangular co ordi nates whose origin is at C in the following equation y=mxir /1--1-m D this straight line passes through the point D whose co.-

ordinates are e, f, and

Therefore this straight line is fully determined by the Equations 1) and E where m is the value in Equation F taking the positive sign.

Next, the thread passing through the thread-guideB for turning the thread will be considered. The thread passing through the point B will not come to any part of the region below the position where the points B, Q and P are on a same straight line; because if it rotates still more, Q will not have any contact with the thread and the thread will be forced to change its course by P. The straight line BP Q (P and Q; are P and Q in the above special position) is the tangent from B tothe circle 20 described above.

Expressing the straight line BP Q by an equation similarly as in the previous case where, m is the value given by the Equation J taking its negative sign.

As explained above, the blade of the thread-cutter does not touch the thread during the normal operation provided that it takes its position on the right side of the straight line CD and on the lower part of the straight line EN. Moreover, as the blade of the thread-cutter is set in the rotation region of the pin P, it is clear that the thread when snapped firmly contacts the blade 21 of the thread-cutter 4 and will be cut 0E.

In Figs. 16a and 16b, 9 is the auxiliary pin provided with a taper and which is made to project out through the passage of the hollow part of the disk 12 near to line PQ (in this case preferably within PCQ) between the said sewing thread take-up pins P, Q. Provision of a third pin R in addition to the said two pins is for the following reason: i

In the operation of a sewing machine, the time when the thread tightens the cloth is required to be within a certain range, according to the kind, thickness and feed of the cloth. Consequently, the time when the thread is detached from the shuttle-body should be within a certain range which may correspond to that. In this case, needless to say, the sewing thread take-up device must meet the requirement of working smoothly within the said certain range. In the case of the thread take-up device with two sewing thread contact pins P, Q between the single-shaft-type complex disks 11, 12, the pulling of thread is effected by means of the pin P alone. Therefore, that operation must necessarily be performed rapidly. Thus, a marked variation in the tension to work on the upper sewing thread due to the difference of the time of thread detachment will be caused, and it may afiect very adversely the operation of the machine.

In view of such an undesirable possibility, adjoining to line PC), which connects the two sewing thread contact pins P, Q set between the single-shaft-type complex disks 11, 12, a third sewing thread contact auxiliary pin R is fixed between P and Q. Thus, in taking up the thread, the two pins, i. e. the sewing thread contact pin P and the auxiliary pin R, operate together so that the thread may be pulled up slowly, and a possible variation in tension due to the difierence in time of thread detachment may be minimized, thereby enabling the sewing machine to operate smoothly within a certain range of the time of thread detachment. In other words, this certain range may be thus arranged so as to be large enough. Furthermore, the third auxiliary pin R works only in the operation of taking up the thread near the upper dead point of the taking-up device, but never in any other phase. Therefore, any possible harmful by-efiects may be guarded against. Further, the projection of the pin R outward from within the hollow part of 'the disk is intended so that the pin may perform the operation of snapping and removing the thread in collaboration with the said thread-cutter 4.

More particularly, it is devised, by making the pin R to act as taper rod, that, when the sewing thread happens to snap during the operation of the sewing machine, the sewing thread 10 may be thrown out by centrifugal force, touched and cut oif by the thread-cutter 4 and twine itself around the pin R; thus the thread is thrown outside of the hollow disk by centrifugal force. In Fig. 16 is illustrated the device under which two hollow disks are provided and two pins 36 are set on points slightly out of mutually corresponding position. With reference to Fig. 16, the positions of the pins on the disks must be lying within the following ranges in the inner and outer disks:

where r is the distance between the pin P or P and the axis C, r is the distance between the pin Q and the axis C and r is the distance between the pin R and the axis C.

Fig. 18 represents a device under which two circular disks are provided and a pair of pins are each set slightly out of mutually corresponding positions, an improvement on that illustrated in Fig. 11. In other words what is shown in Fig. 11 denotes, in the case of illustration of Fig. 18, a case where, in doubling the threads between disks, the sewing thread take-up pins on the respective disks touched by each of the threads doubled are lying at the same point. In the case of illustration of Fig. 11, friction is caused at the turning thread guide by duplicating the thread on the disks, the tightening of the thread is influenced thereby and sewing conditions tended to make the upper thread rather Weak. It is because the sewing thread contact pins of the duplicated thread on the inner and outer disks are in the same positions and performed the same variations of phases and, therefore, in tightening the thread on the cloth, the thread is pulled from the cloth and'from the conditioning disk and, before the thread tightening of the cloth is suflicient, thread winding is started from the conditioning disk.

In the plural disks shown in Fig. 18, the positions of the pins of the inner disk are displaced from those of the outer disk, setting the time of the higest takeup the sewing thread by the inner pins with the rotation of the main shaft about 20 to 30 in advance of that by the outer pins, and therefore, when the thread is to be actually tightened, the take-up of the sewing thread by the inner disk has already been completed and then the take-up is performed only by the outer disk.

Within the range of 20 to 30 before the highest position in the thread take-up curve, thread take-up by the inner disk has already'been completed and thread take up only by the outer disk goes on. That is, the amount'of take-up corresponding to approximately 10 mm. (3 to 10mm.) at the top of the thread take-up curve is given only by the outer disk and the curve by the-inner disk hardly varies, showing no rise atall but being rather made to fall a little. From this fact, when the thread on the cloth is tightened, the passage of the thread from the thread conditioning disk through the inner-pins to the turning thread guide is presumed to be static and is not performing any positive operation for tightening the thread. At the other time than of tightening the thread, the tension of the thread, even. if applied, is hardly strong. Thus, the fact that the thread is hung doubly has no trouble in fact. From the above explanation, it can be said that, in the period of tightening the thread in the operation of taking up the thread, only the outer pins operate and that this is, in fact, exactly the same as in the single plate thread taking up device.

With reference to Figure 18, the positions of the pins and outer disks:

where, r and r are the distances of the pins on the inner disk from the axis and r, and r are the distances of the pins on the outer disk from the axis. A is an angle between the preceding pins on the inner and outer disks with respect to the center of the axis. a is an angle between the two contact members on the front disk. 8 is an angle between the two contact bodies on the rear disk. A, and C, wherein the curve C represents the variation of the amount of take-up of the sewing thread in case where the above-mentioned auxiliary pin (R)- is provided at a variable position within the triangle. CPQ according to this invention, the curve A repre-- sents the corresponding variation in case of short of the auxiliary pin R as usual, the curve Tc represents the variation of tension subjected to the needle thread depending upon the variation in the thread-separating period in the first-named case, the curve Ta represents the variation of the corresponding tension in the secondnamed case, the curve A represents the variation similar to the same represented by the curve A but the action of a thread take-up spring also being considered therein, and the curve C represents the variations similar to the variation represented by the curve A and corresponding to the curve C.

In case where the auxiliary pin R is not provided as shown in Fig. 14, the curve A representing the variation of the amount of take-up of the sewing thread is larger than the other coupled case in the proximity of the lower dead point of the take-up device resulting in that the variation Ta of tension subjected to the needle thread depending upon the variation in the thread-separating period is made larger than the other case. Such an enlarged variation Ta of tension subjected to the needle thread depending upon the variation in the thread-separating period ends in various disadvantages for varying the thread-setting period in accordance with kind, thick-' ness, and feed of the cloth, resulting in, in turn, that it becomes possible to define the range sufficiently broadly within which the thread-setting period may be adjusted in order to meet the kind, the thickness, and the feed of lower dead point of the take-up device resulting in that.

the variation Tc of tension subjected tothe needle thread depending upon the variation in the' thread-separating" Fig. 19 shows six curves C, A, Tc, Ta,

narrowed variation Tc of tension subjected 'to. the. needle thread depending upon the variation in the threadsep- 'arating period ends in such a benefit for varying the thread-setting period in accordance with the kind, the.

thickness, and the feed of the cloth that it becomes possible to define the range sufficiently broadly for ad justing the thread-setting period within it.

Thus it may be seen that the third, auxiliary, thread take-up pin R provided at a .specified position as set forth hereinbefore bears such industrial effects as to flatten the thread take-up action in the proximity of the lower dead point of the thread take-up device selectively ending in to broaden the adjustable range for the thread-setting period and to smooth the sewing operation of the machine.

According to this invention, three discs and four pins are arranged as follows: Two pins are arranged across the inner space between the inner disc and the middle disc and the other two pins are arranged across the outerspace between the middle disc and the outer disc, a pin across the inner space being arranged in alignment with a pin across the outer space and radially inwardly, while the other pin across the inner space being arranged slightly out of alignment with the other pin across the outer space and radially outer than the first-named two pins. By virtue of the arrangement as above, in the tightening actionof thread a machine according to this invention is improved comparing with a take-up device where two pairs of pins are arranged in alignment with each other, respectively. As faras such an efiect. is attained, it must be considered that this fact also contributes to the patentability of this invention.

Fig. .20 is a diagram showing the variation in course of the sewing thread with the amount of thread sent out in the ordinate and the angle or rotation of the main shaft in the abscissa. Curve T represents the variation in the amount of the taken-up thread by means of the inside pins. Curve T represents the variation in the amount of the taken-up thread by means of the outside pins. Curve T represents the composite variation composed of the above two.

The variation in angle between 4 and 5:

The variation in the amount of the taken-up threads:

H--'-5-10 mm It may be seen that by virtue of the arrangement in the above outside pins act only during the period for tightening the cloth during the thread take-up, thereby the tightening of the cloth becomes sufiiciently intensive. Furthermore, the operation of the thread takeup is thus on the whole made to cooperate rationally with the operations of the needle spindle, the rotary hook mechanism, and the feeding mechanism of the sewing machine. It becomes thus possible to find a sewing condition where sewing quality may be kept invariable regardless the variation in speed.

In Figs. 1 to 3, 28 is a lever which connects the crank on the side of the main shaft 7 with the needle rod 15, and beneath this lever is a sliding projection 30 to fit in the up and down guide-grooves 29, is fixed concentrically with respect to the lever fitting hole 31 at the upper end of the needle rod 15. 32 is the balance weight of the crank on the side of the main shaft 7. 35 represents a half-oscillating-type shuttle.

Figs. 5 to are given to show the various aspects, during in operation, of the sewing machine under this invention. As regards the measurement of the angle of the crank in these figures, the standard formulae adopted are as follows: In the case of the angle of the crank on the side of the thread take-up device the angle of zero p=0) is decided to be the standard angle which is. formed at the time when the pin of the threadtake 10 up device is lying along the horizontal line including the center of the thread take-up device C on the opposite side of the thread-guide for turning the thread. In the case of the angle of the crank on the side of the main shaft to, the angle of zero (w=0) is decided to be the standard angle which is formed at the time when the line of the axle of the crank 3 is lying along the vertical line including the center of the main shaft. In other words, the above angle at is zero when the needle-rod is lying at the upper dead point. the graphs shown in Figure 9, distances along abcissa indicated by the lines ww" and the like are as follows:

ww' corresponds to phase upper dead point of needle-rod uu' corresponds to phase upper dead point of take-up device tt corresponds to phase thread leaving off ss corresponds to phase thread detachment rr' corresponds to phase lower dead point of take-up device qq' corresponds to phase thread hanging pp corresponds to phase lower dead point of needle-rod 00 corresponds to phase sinking down of eye of needle,

and

nn corresponds to phase sinking down of tip of needle.

' Thus the graphs shows one complete cycle of operation in the household sewing machine.

Fig. 5 shows the situation wherein the angle (,9 of the crank on the side of the thread take-up device is at 0, which corresponds to the time immediately preceding the passing of the sewing thread through the shuttlebody. At this time the angle to of the crank on the side of the main shaft forms around 20.5 degrees, which corresponds to the phase indicated by I in Fig. 9-a (in curve K), wherein the ordinate Y gives the amount of take-up of the sewing thread and the abscissa X the angle of rotation of the main shaft.

Fig. 6 shows the situation wherein the above-mentioned angle ,0 forms degrees, which corresponds to the intermediate period between the passing of the sewing thread through the shuttle-body and the drawing in of of the needle-eye under the needle-plate, when the angle a: of the crank on the side of the main shaft forms around 79 degrees, which corresponds to the period shown by II of Fig. 9.

Fig. 7 indicates the time when the angle (,0 of the crank on the side of the thread take-up device forms 180 degrees, which is a little prior to the phase of lowest point of needle-rod, and then the angle to of the crank on the side of the main shaft is around 158.5 degrees, and corresponds to the phase shown in III of Fig. 9. Fig. 8 shows the situation wherein the above-mentioned angle (p forms 270 degrees, which. corresponds to the intermediate phase of the rapid increase of the amount of the sewing thread drawn in under the needle-plate. On the other hand, the angle to of the crank on the side of the main shaft then is around 305 degrees, which corresponds to the period shown IV of Fig. 9. Further as illustrated by Fig. 9, on the period corresponding to that half-way between IV and I falls the period when the mount of take-up of the sewing thread is at a maximum. The angle p of rotation of the main shaft for pulling the sewing thread to the uppermost repre sents the space of time covering this period and that when the amount of take-up of the sewing thread is at a minimum, which lies half-way between I and II. This angle measures, in the case of ahousehold sewing machine, approximately 90 degrees as indicated by' curve K, and in the case of an industrial sewing machine, approximately 'degrees (see Fig. 9), as indicated by curve L. In this invention, as clearly shown in Fig. 9, in making the velocity of rotation of the crank on the thread take-up device 2' to be the nonuniform velocity based on the conditions under the above-mentioned expressions S, T, U and W which are indicated in Fig. 10,.

And in '11 the positions of the above-mentioned sewing thread takeup pins 13, 14 are decided so as to be specifically related with each other as indicated above by expressions J, K, M and N. In so doing, as illustrated by Fig. 15, wherein ww shows the position of'the upper dead point of the needle-rod and an (u u or u u or 11 21 shows the position of the upper dead point of the take-up device, the position of the upper dead point of the take-up device will be lying within the range of 55 to 75 degrees with reference to the upper dead point of needle-rod, thus shortening specially the period of pulling up the sewing thread and thereby enabling the angle t of rotation of the main shaft necessary for pulling up the sewing thread to the uppermost to be narrowed approximately to 80 degrees. Besides, as shown in Fig. 9, the characteristic curve represented by curve K is approximately the same as that of a household sewing machine equipped with the usual cam-type thread take-up device. Further, with respect to the relationship between curve K and curve L in Fig. 9-a, both curves are those of take-up of the sewing thread with the same pins P, Q and threadguides A, B, D, while curve L is shown at the time of the disk 11 being at uniform velocity and curve K at the time of the disk 11 being at nonuniform velocity as in the case of this invention. It has to be noted that the lowest dead point each of both curves have been represented to be on the same position for the sake of convenience. Curve M is the curve of variation of the amount of the sewing thread drawn in under the needleplate of a half-oscillating type shuttle for household use. From this curve M and the above curve K and curve L are obtained the corresponding curves of variation of the amount of the loosening of the sewing thread during one cycle of operation in making seams. That is curves K and L in Fig. 9-b are curves of variation of the amount of loosening of the sewing thread which correspond to the said curves K and L respectively. Straight line N shows the amount of loosening of the sewing thread at zero; the upper side of the line indicates the amount of loosening of the sewing thread, and the lower side of it the amount of tensioning of the sewing thread. In the drawing curve L indicates that the thread is tensioned for the period from a little after the phase of the upper dead point of the take-up device to near the phase of the lower dead point of the needle rod. In other words, it indicates that the operation of sewing in making seams is made impossible by this tensioning of thread. Whereas, it can be understood from the drawing that, as shown by curve K with reference to the sewing machine under this invention such tensioning of thread may be ceased and consequently adequate amount of loosening of thread may be ensured, thereby enabling the satisfactory sewing opera-- tion.

Another reason for which satisfactory performance of sewing can be achieved by employing the sewing machine under this invention is that, under above construction, the angle l/ for pulling up the sewing thread to the uppermost point may be narrowed to 80 or thereabouts, thus enabling the tightening of the cloth by the thread to be completed speedily. In other words, in the case of the existing sewing machines including those of the cam-type thread take-up device, a considerable length of time is required between the passage of the sewing needle through the cloth and the tightening of the cloth by the thread, and therefore such sewing machines have not been free from the defects that make good sewing diiiicult to be done. Generally, it is a requisite for ensuring good sewing that the cloth be tightened by the threadbefore much time elapses after the passage of the sewing needle through the cloth. Whereas, as a matter of fact, this requirement has not been met owing tothe delayed tightening of the cloth by the thread take-up device. (In the case of a cam-type thread takeup.device,,it has. been =diificult= to narrow theangle for I2 pulling up the sewing thread to the upper-most point.) In the case of this inventiomhowever, full advantage can be taken of the above-mentioned construction.

Therefore, the angle ,0 for pulling up the sewing thread to the uppermost point can be narrowed approximately to the tightening of the cloth by the thread by means of the thread take-up device can be done quickly; and thus the tightening of the cloth can be completed before much time elapses after passage of the sewing needle through the cloth. In this respect this device can perfectly fulfil the requirement referred to above, and thus enables us to be assured of remarkably fine performance of sewing as compared with that under the existing device.

As stated above, this invention has its conspicuous merit in that it has for its object the provision of a sewing machine for household use equipped with both the various strong points possessed by that of a single shaft-type take-up device and also advantages drawn from a half-oscillating type shuttle, by making in the case of a sewing machine with a single shaft thread takeup device, the characteristic curve of the device approximately the same as the corresponding one of an ordinary household sewing machine which is equipped with a half-oscillating type shuttle with a cam-type thread take-- up device, and also having the device by which a fine result can be achieved in sewing by the speedy completion of rational supply, the pulling-up of the thread and the tightening of the cloth by the thread.

We claim:

1. A household sewing machine comprisinga frame, a main shaft, a thread take-up device, a needle rod, means for oscillating the needle rod along a straight needle rod line, and a half-oscillating type shuttle, said take-up device comprising at least one disc, a plurality of threadguide pins comprising two stationary thread guide pins provided adjacent the edge of said disc one near the other, and one being lower than the other and a stationary thread-turning guide pin provided adjacent the edge of said disc at a point opposite to the two stationary thread guides, said disc being journaled rotatably in said frame and eccentrically arranged relative to said main shaft, said disc being driven by the main shaft in such a manner relative to said main shaft that the angular speed of the drive shaft varies from the angular speed of the disc when the former is driven from the latter at a variable speed, a double crank mechanism comprising a driving crank arm, a following crank arm, and a link rod connecting the arms, said crank mechanism driving the disc and being conditional on Where E is the eccentricity between two axes of the two crank arms or the eccentricity between said disc and said main shaft, R is the length of the driving crank arm, L

is the length of the link rod connecting the two crank arms and R is the length of the following crank arm, and said disc comprising at least two pins fixed thereon, one of said two pins being positioned more remotely from the center of said disc than the other conditional on a ratio of the distance between said other and said center to the distance between said one and said center 'being in a range of 0.5 to 0.75, and an angle extending half-oscillating type shuttle, by means of limiting an angle 2 of eccentricity placed between a straight line innewness cluding the centers of said main shaft and said disc and said straight needle rod line within a range between +20 and 20 and selecting an angle 6 within a range between 170 and 210, the last-named 6 being placed between said one more remotely positioned of said two thread contacting pins and said thread-turning guide pin at the center of said disc when said needle rod is in the highest position.

2. A household sewing machine as claimed in claim 1, said take-up device comprising a'pair of discs having a single shaft and further comprising a thread cutter having a blade positioned within a sector and an angle, said sector being defined by two hypothetical lines of contact and a hypothetical circle, said hypothetical lines being extended from the lower thread guide and the threadturning guide, respectively, said plurality of thread-guide pins including an intermediately positioned pin, another hypothetical straight line connecting the outermostly positioned one of said thread contacting pins and the innermostly positioned one of said thread contacting pins in alignment, and being extended and contacting with said hypothetical circle, said hypothetical circle being centered on the center ofsaid disc and passing on a point slightly inwardly of the position of the intermediately positioned pin of said thread contacting pins, and said angle being placed between two straight lines, one connecting the center of the discs with said thread-turning guide and the other connecting the center of discs with said lower thread guide.

3. A household sewing machine as claimed in claim 1, wherein an auxiliary, third, thread-contacting pin is provided and is positioned within a hypothetical triangle defined by the two thread-contacting pins and the center of the disc.

4. A household sewing machine as claimed in claim 2, the intermediately positioned pin is located within a hypothetical triangle defined by the two thread-contacting pins and the center of the disc.

5. A household sewing machine as claimed in claim 1, wherein the thread take-up is eflected by the thread-contacting pin provided on the inside disc prior to thread take-up effected by the thread-contacting pin provided on the outside disc, and final tightening action subjected to a cloth is effected by the latter pin, according to the rotation of the main shaft.

6. A household sewing machine as claimed in claim 1, wherein after the end of the thread take-up action effected by the thread-contacting pin provided on the inside disc and prior to beginning of the cloth tightening action effected by the thread-contacting pin provided on the outside disc 3 to 10 mm. of thread in length is taken up by the second-named thread-contacting pin.

7. A household sewing machine comprising a frame, a main shaft, a thread take-up device, a needle rod, means I for oscillating the needle rod along a straight needle rod line, and a half-oscillating type shuttle, said take-up device comprising at least one disc a plurality of thread guides comprising, two stationary thread guides provided adjacent the edge of said disc, one near the other, and a stationary thread-turning guide provided adjacent the edge of said disc at a point opposite to the two stationary thread guides, said disc being journaled rotatably in said frame and eccentrically relating to said main shaft, and driven therefrom at a variable speed by means of a double crank mechanism comprising a driving crank arm, a following crank arm, and a link rod conditional on where E is the eccentricity between two axes of the two crank arms or the eccentricity between said disc and said 14 main shaft, R is the length of the driving crank arm, L is the length of the link rod connecting the two crank arms,

and R is the length'of the following crank arm, and said disc comprising at least two thread contacting pins fixed thereon, one of said two pins being positioned more remotely from the center of said disc than the other conditional on a ratio of the distance between said other and said center to the distance between said one and said center being in a range of 0.5 to 0.75, and an angle extending from to being placed between said two pins at the center of said disc, an angle extending from 90 to being placed betweeneach of the first named thread guides and said thread-turning guide at the center of said disc, and the last-named angle averaging from 100 to 130; characterised in that the angle (,0 of rotation of said main shaft for pulling the sewing thread to the uppermost is less than 90, so as to be adaptable to said half-oscillating type shuttle, by means of limiting an angle 1: of eccentricity 'placed between a straight line including the centers of said main shaft and said disc and said straight needle rod line within a range between +20 and 20 and selecting an angle 6 within a range between and 210, the last-named angle 6 being placed between said one more remotely positioned of said two thread contacting pins and said thread-turning guide at the center of said disc when said needle rod is in the highest position.

8. A household sewing machine as claimed in claim 7,

in which the take-up device comprises a pair of discs having a single shaft and further comprising a thread cutter having a blade positioned within a sector and an angle, said sector being defined by two hypothetical lines of contact and a hypothetical circle, said hypothetical lines being extended from one of the thread guides which is lowermost and the thread-turning guide, respectively, said plurality of thread guides including an intermediately positioned pin, said thread-contacting pins being provided between said pair of discs, another hypothetical straight line connecting the outermostly positioned one of said thread contacting pins and the innermostly positioned one of said thread contacting pins in alignment, and being extended and contacting with said hypothetical circle, said hypothetical circle being centered on the center of said discs and passing on a point slightly inward of the position of said intermediately positioned pin of said thread contacting pins, and said angle being placed between two straight lines, one connecting the center of discs with said thread-turning guide and the other connecting the center of discs with said lower thread guide.

9. A household sewing machine as claimed in claim 7, wherein an auxiliary, third, thread-contacting pin is provided being positioned within a hypothetical triangle defined by the two thread-contacting pins and the center of the disc.

10. A household sewing machine as claimed in claim 7, wherein thread take-up is effected by the thread-contacting pin provided on the inside disc prior to thread take-up effected by the thread-contacting pin provided on the outside disc, and final tightneing action subjected to a cloth is effected by the latter pin, according to the rotation of the main shaft.

References Cited in the file of this patent UNITED STATES PATENTS 

